This was interesting.

 

After many many weeks of trawling through official embassy information, checklists of visa agencies, forums, it became clear non of them offered sound advice, nor clearly identified the documents required. 
     After many wasted visits to official offices, did I finally discover the true route.

 

example:

as a Sponsor to a visa, proving financial means, subsistence.

bank statements, not good enough downloaded must be signed stamped by bank, at least 3 months, 6 months, minimum thus much, that much,

  health insurance minimum this much, minimum that much, flight tickets, itenary, trip schedules, invitation letters, proof of accomodation,  etc etc etc etc 

 

all this info you read.

 

finally I found the way, which I could not find advised on internet anywhere, not even on embassy if vfs agent websites. 
 

all the above is <deleted>.

 

actually whats needed.

Invitation letter from Czech Foreign police.

 

thats all.

 

to get that you simple fill in a form, 

show a stamped note from your bank showing your account balance is above the minimum requirement set out by the schengen rules (each country has different amounts)

 

5 minutes later you have a verified invitation letter signed and stamped from foreign police.

    
At the embassy in Thailand no need to show any further confirmation of financial means, accomodation, etc etc, nothing. 
 

that 1 document proves it all.

job done.

Interesting, but not 100% clear - therefore a couple of questions to clarify:

• Did you apply for this Police Invitation Letter in order to invite a (girl)friend to your Schengen home-country?
• If so, can this Police invitation Letter only be provided by Czech Police (which you mentioned), or is it similar for all Schengen countries?
• Was the Police invitation Letter the only document required to be granted the Visa to visit the Schengen country?  Obviously also the applicant's passport and filled-in Visa application form would be required.

Thanks in advance for clarifying the above.